This is very strange and we can't catch this behavior. I think this message (it is directly from Vista's scheduler) appears only when using some particular settings. Could you send us a sample project that always reproduces this error?

I'm sorry, but we don't need EXE sample as we can't debug it. We need source sample to see what code causes that error message and try to debug it. Also, as you see the error comes from system DLL and could be a bug in Vista's Scheduler itself.

Are you able to reproduce this when using Quick Demos from the Demo project? There is item named "Run notepad.exe every day at 09:00" which creates daily task. We've tested this on our side and it works just fine.